In general, a refrigerator is used to maintain the freshness of various food for a long duration by supplying cool air generated by an evaporator to a storage room. The storage room of the refrigerator is partitioned into a refrigerating compartment that is maintained at about 3° C. to keep food refrigerated, and a freezing compartment that is maintained at about −20° C. to keep food frozen.
The freezing compartment stores food (for example, meat, fish, and frozen dessert) that needs to be maintained under a freezing temperature, and the refrigerating compartment stores food (for example, vegetables, fruits, and drinks) that needs to be maintained above a freezing temperature.
The refrigerator is driven in a cooling cycle in which refrigerant is successively compressed, condensed, expanded, and evaporated through a compressor, a condenser, an expander, and an evaporator, respectively. According to the kinds of refrigerators, a single evaporator placed in a freezing compartment cools both the freezing compartment and a refrigerating compartment, or evaporators are respectively placed in a freezing compartment and a refrigerating compartment to cool the freezing compartment and the refrigerating compartment independently.
In the evaporator, refrigerant in a liquid state is evaporated to take away evaporation heat from surrounding air to thereby cool the surrounding air. Evaporators are classified into a direct cooling type evaporator and an indirect cooling type evaporator. The direct cooling type evaporator has low consumption power and excellent cooling performance since it performs heat exchange directly inside a storage room. In contrast, in the indirect cooling type evaporator, cool air cooled in space spaced from a storage room moves to the storage room by a fan. The indirect cooling type evaporator has excellent heat exchange efficiency and can reduce the generation of frost around the evaporator since it can be entirely used. Comparing the indirect cooling type evaporator to the direct cooling type evaporator, the indirect cooling type evaporator requires a fan to circulate cool air into the storage room, and a defrosting heater to process defrost water that is generated from the evaporator and an evaporator cover.